IB Biology: Reproduction & Hormones FAQ

It's the study of human reproductive anatomy, gametogenesis, the menstrual cycle and the hormones controlling it (FSH, LH, oestrogen, progesterone, testosterone), taught under Topic D3 Reproduction with links to C3 Integration of body systems. It's examined across Paper 1 (multiple choice), Paper 2 (short/extended response, often with data), and Paper 3 (option-linked questions for some HL students).

Core content includes male and female reproductive anatomy, spermatogenesis and oogenesis, the roles of FSH, LH, oestrogen and progesterone in the menstrual cycle, fertilisation, and hormonal control of pregnancy, labour and lactation. HL adds IVF, secondary sexual characteristics and negative/positive feedback loops in more depth.

Most of it is common core, so both SL and HL students study the basic anatomy, gametogenesis and the four main menstrual cycle hormones. HL students get extra depth — secondary sexual characteristics, more detail on assisted reproductive technology, and tighter expectations around feedback mechanisms in exam answers.

Because four hormones interact through both positive and negative feedback within a single 28-day cycle, and most students try to memorise the graph shape without understanding why each peak happens. I've marked hundreds of scripts where students get oestrogen and progesterone's timing backwards under exam pressure.

FSH stimulates follicle development in the ovary; LH triggers ovulation via a mid-cycle surge; oestrogen (from the developing follicle) rebuilds the uterine lining and eventually triggers that LH surge; progesterone (from the corpus luteum) maintains the lining and suppresses FSH/LH once ovulation has occurred.

The biggest one: writing that progesterone 'increases' throughout the whole cycle instead of specifically after ovulation. Others include confusing which gland releases which hormone, forgetting to name the feedback type (positive vs negative), and failing to link a graph's data points to the biology when asked to explain, not just describe.

Draw the four-hormone graph from memory, then annotate every peak and trough with the cause and the effect — don't just label the axes. Practise past paper data-based questions on this exact topic, since examiners reuse the same graph-interpretation structure most series.

Link each hormone to its source gland and its single main job rather than a long list of effects — FSH: follicle growth; LH: ovulation trigger; oestrogen: lining rebuild + LH surge; progesterone: lining maintenance + FSH/LH suppression. One clean sentence per hormone beats a paragraph you'll forget under pressure.

Yes — this topic appears almost every exam series, usually as a data-based question showing a hormone concentration graph across the menstrual cycle, sometimes combined with a scenario about fertility treatment or contraception. RevisionPrep's Topical Worksheets and Mock Papers include IB-style questions specifically built around this graph format.

It varies by series, but expect roughly 6-10 marks combined across Paper 1 and Paper 2 in a typical exam sitting, often split between one or two multiple-choice questions and a data-based question worth 4-6 marks on the menstrual cycle or hormonal control of pregnancy.

All three are possible. Paper 1 tests recall of hormone functions via multiple choice; Paper 2 is where the graph-based, data-response questions on the menstrual cycle usually appear; Paper 3 can bring it in if a student's chosen option links to human physiology or reproduction.

Both cover the menstrual cycle hormones and human reproductive anatomy in similar depth, but IB Biology frames it within a concept-based, data-analysis approach — students are regularly asked to interpret unfamiliar hormone graphs rather than just recall facts, which suits students comfortable with applying knowledge, not just reciting it.

Look for materials built around the actual 2025 DP Biology guide rather than generic biology content — topic-specific Revision Notes covering D3 Reproduction, Topical Worksheets with graph-based practice questions, and full Mock Papers so your child sees how the topic actually gets combined with other content under timed conditions.